Field of the Invention
The present invention relates to loudspeakers and systems for the high fidelity reproduction of sound. In particular, the present invention relates to full spectrum loudspeakers designed for close proximity and near field use.
Description of Related Art
Passive radiators (also called passive speakers or passive loudspeakers) are known in audio speaker design. A passive radiator is a radiating diaphragm which is suspended by a compliant suspension component, and whose back surface shares an enclosed air volume with that of an active transducer (speaker or loudspeaker). The movement of the active speaker's diaphragm pressurizing and depressurizing causes the passive speaker to vibrate. The sound produced by the passive speaker adds to the sound produced by the active speaker and increases the overall sound pressure level produced by the entire system.
Audio reproduction incorporates the original designs of active speakers, employing magnets and cone materials to transfer the electronic waves through voice coils, moving the cone material to produce audible sounds the ear can understand. To overcome the back-wave problems inherent with speaker systems, enclosures of all sorts have been developed, with varying formulas and mathematical theories to improve the output of the speakers, i.e. to improve the sound.
A push pull design, where at least two speakers are wired out of phase, was developed and applied in various patents since the 1920's. For example, these patents cover designs wherein the loudspeakers are facing each other, with the same phasing, and also designs with loudspeakers facing opposite directions and out of phase. This allows the two loudspeakers to act as one. Even with the improved response, the remaining need is with low frequency reproduction.
Engineers, inventors, and mathematicians have creatively changed and improved the equations dealing with reproduction of low frequencies, but the paradigm for accomplishing that has not changed. The current technology incorporates large enclosures, or large sized loudspeakers, or a combination of both, to produce the low frequency response required for the current market. In addition, use of crossover circuits and multiple speakers covering different parts of the audible spectrum are utilized. The result is that speaker systems reproducing accurate bass take up a lot of room.
Accordingly, a speaker system which allows for rich full frequency reproduction in a small enclosure is still something the industry is searching for and users would appreciate, especially in situations with small areas for placement of speakers, such as in a small room or inside furniture or light fixtures. Sub woofers are an example of addressing the issue, but subwoofers deal with only the low lows. There are still crossover problems present in this type of speaker system.